Quadriceps weakness, patella alta, and structural features of patellofemoral osteoarthritis

NIH Public Access Author Manuscript Arthritis Care Res (Hoboken). Author manuscript; available in PMC 2012 October 1.

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Published in final edited form as: Arthritis Care Res (Hoboken). 2011 October ; 63(10): 1391–1397. doi:10.1002/acr.20528.

Quadriceps Weakness, Patella Alta and Structural Features of Patellofemoral Osteoarthritis: The Multicenter Osteoarthritis Study Joshua J. Stefanik, MSPT, PhD.1, Ali Guermazi, MD1, Yanyan Zhu, DSc.1, Ann C. Zumwalt, PhD1, K. Douglas Gross, PT, ScD1,2, Margaret Clancy, MPH1, John A. Lynch, PhD3, Neil A. Segal, MD4, Cora E. Lewis5, Frank W. Roemer, MD1,6, Christopher M. Powers, PT, PhD7, and David T. Felson, MD, MPH1 1Boston University School of Medicine, Boston, Massachusetts 2Massachusetts

General Hospital Institute for Health Professions, Boston, Massachusetts

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3University

of California, San Francisco, CA

4University

of Iowa, Iowa City, IA

5University

of Alabama, Birmingham, AL

6Department 7University

of Radiology, Klinikum Augsburg, Augsburg, Germany

of Southern California, Los Angeles, CA

Abstract Objective—To determine the relationship between quadriceps weakness and cartilage damage and bone marrow lesions (BMLs) in the patellofemoral joint (PFJ), and if this relationship is modified by patella alta.

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Methods—The Multicenter Osteoarthritis (MOST) Study is a cohort study of persons aged 50– 79 years with or at risk for knee OA. Concentric knee extensor strength was measured using an isokinetic dynamometer. Patella alta was measured using the Insall-Salvati ratio (ISR) on the lateral radiograph, and cartilage damage and bone marrow lesions (BMLs) were graded on MRI in the PFJ. We determined the association between quadriceps weakness with cartilage damage and BMLs in the PFJ among those knees with (ISR≥1.2) and without patella alta (ISR